Lead in dry river sediment was extracted with 25 wt% HNO3 at incubation temperatures for 1 hr. Then 1 mL of filtered extract was combined with other reagents to a total of 4.60 mL. Pb+2 was measured by an electrochemical method by spiking with 2.50 ppm Pb2+. added vol. of 2.50ppm Pb2 signal 0 mL 1.10 0.025 mL 1.66 .050 mL 2.20 .075 mL 2.81 what is Sx based on Sy

Lead in dry river sediment was extracted with 25 wt% HNO3 at incubation temperatures for 1 hr. Then 1 mL of filtered extract was combined with other reagents to a total of 4.60 mL. Pb+2 was measured by an electrochemical method by spiking with 2.50 ppm Pb2+. added vol. of 2.50ppm Pb2 signal 0 mL 1.10 0.025 mL 1.66 .050 mL 2.20 .075 mL 2.81 what is Sx based on Sy

Principles of Instrumental Analysis

7th Edition

ISBN:9781305577213

Author:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Publisher:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Chapter30: Capillary Electrophoresis, Electrochromatography, And Field-flow Fractionation

Section: Chapter Questions

Problem 30.6QAP

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A sample of steel (0.506 g) was digested in acid and the solution made up to 100 cm3 with deionised water. Aliquots (25.0 cm3) of this solution were transferred into two volumetric flasks (100 cm3) labelled A and B. Flask A was made up to volume with deionised water. To flask B was added 10.0 cm3 of a 260 ppm standard solution of Mn2+ which was then also made up to volume with deionised water. The following absorbance results were obtained: Solution A = 0.356, Solution B = 0.578. Use these results to calculate the percentage (% w/w) of manganese in the steel sample.
Six iron tablets containing FeSO4.7H2O were dissolved in 100-ml of 0.1M HNO3 with gentle heating. All of the Fe2+ is converted to Fe3+ by the strong oxidizing conditions. After the solution had cooled to room temperature , 2.5-ml of 35wt% NH4OH was added. The precipitate Fe2O3-xH2O that was filtered weighed 0.345g. Thermogravimetric analysis of the crude product showed a 10.5% weight loss . A. How many waters of hydration were in the precipitate B. How much iron is present in each tablet
For Indirect Iodometric Analysis of Copper... ~0.0896g KIO3 necessary to consume 350mL of 0.1 M Na2S2O3, Na2S2O3 is stored in an amber glass bottle until ready for use. Primary Standard KIO3 has 2g of KI, 50mL of DI water, and 10 mL of 1.0M HCl is added then immediately titrated with Na2S2O3 until medium yellow or straw... then 5mL of starch indicator is added and titrated again until blue black color turns clear. Unknown CuO use 1.2G of Unknown, 20mL of HNO3 heated until sample dissolved, 25 mL of DI water added and boiled until clear light blue color, after cooling 1:1 NH3 added (~34.47 mL of NH4OH reagent) until permanent deep blue color amine complex, 2g of NH4HF2 added and swirled until dissolved, 3 g of KI is added then titrated immediately with Na2S2O3 until brown color of iodide is nearly gone (brown milk color), 2 g of KSCN and 3 mL of starch indicator is then added with titration continuing until disappearance of new blue black color. 1. Na2CO3 is often added to thiosulfate…
For Indirect Iodometric Analysis of Copper... ~0.0896g KIO3 necessary to consume 350mL of 0.1 M Na2S2O3, Na2S2O3 is stored in an amber glass bottle until ready for use. Primary Standard KIO3 has 2g of KI, 50mL of DI water, and 10 mL of 1.0M HCl is added then immediately titrated with Na2S2O3 until medium yellow or straw... then 5mL of starch indicator is added and titrated again until blue black color turns clear. Unknown CuO use 1.2G of Unknown, 20mL of HNO3 heated until sample dissolved, 25 mL of DI water added and boiled until clear light blue color, after cooling 1:1 NH3 added (~34.47 mL of NH4OH reagent) until permanent deep blue color amine complex, 2g of NH4HF2 added and swirled until dissolved, 3 g of KI is added then titrated immediately with Na2S2O3 until brown color of iodide is nearly gone (brown milk color), 2 g of KSCN and 3 mL of starch indicator is then added with titration continuing until disappearance of new blue black color. 4. Why is the starch indicator solution…
Suppose you have a soil that is made up of 10% organic matter with CEC = 200 cmol/kg, 40% kaolinitewith CEC = 10 cmol/kg, and 50% vermiculite with CEC = 100 cmol/kg.1- Calculate the overall CEC of the soil by taking a weighted average of the three soil components.2- What percentage of the overall CEC is contributed by the organic matter? How does that numbercompare to the 10% of the soil itself that is organic?
A sample of body serum is to be analysed for sodium by flame emission spectroscopy. 1.00cm' aliquot of serum was pipetted into each of two 50.0cm' volumetric flasks. The first flask was diluted to volume with deionised water. The absorbance of this first solution was0.350. To the second flask 10.0 cm' of a 25.0 ppm sodium standard was added and the flask made up to volume with deionised water. The absorbance of this second solution was 0.720.(i) Calculate the concentration of the sodium in the body serum in mg dm-3.
A chemist received different mixtures for analysis with the statement that they contained NaOH, NaHCO3, Na2CO3, or compatible mixtures of these substances, together with inert material. From the data given, identify the respective materials, and calculate the percentage of each component. 1.000g samples and 0.2500N HCl were used in all cases. (A) For Sample W: With PP, 24.32ml was used. A duplicate sample required 48.64ml with MO. (B). For Sample X: The addition of PP caused no color change. With MO, 38.47ml of the acid was required. (C). For Sample Y: To cause a color change in the cold with PP, 15.29ml of the acid was necessary, and an additional 33.19ml was required for complete neutralization. (D) For Sample Z: The sample was titrated with acid until the pink of PP disappeared; this process required 39.96ml. On adding an excess of the acid, boiling, and titrating back with alkali, it was found that the alkali was exactly equivalent to the excess acid added.
A sample of iron ore weighing 800 mg was treated with HNO3 , boiled to dryness and redissolved in dilute HCl. After filtration and removal of undissolved silica, the liquid was passed through a Walden reductor. The collected sample was titrated with 0.0210 M KMnO4 , requiring 12.0 mL to reach the end point. Calc %Fe (55.845) in the ore.
A 1.000-gram sample of NaOH (39.997 g/mol) which has been exposed to the air for some time (NaOH will adsorb water and CO2 from the ambient air) is dissolved in water and then diluted to 500.00 mL. 100.0 mL of this solution required 38.60 mL of 0.1062 M HCl to be titrated to the endpoint (~pH 3). A second 100.00 mL portion is treated with excess BaCl2 and then diluted to 250 mL and filtered. 200 mL of the filtrate required 29.62 mL of HCl to titrate to the (~pH 8-9) endpoint. Calculate the mass percentage of NaOH and Na2CO3 (105.9898 g/mol) in the original sample. The adsorbed CO2 is converted to Na2CO3. The Ksp for BaCO3 (s) is 2.58 x 10-9.
In a beaker 20mL of 0.5M Ca(OH)2 and 80mL of 0.5M CH3COOH are mixed and then this mixture is added on 2g of active coal. After waiting for about 20 minutes the solution is filtered and the filter is titrated by 1M NaOH solution in the presence of an indicator. 10mL of the NaOH solution has been used. Calculate the amount of acetic acid adsorbed per gram of the coal in moles. Explain all the steps and reactions of the experimental process by your own comments.
A 0.0200 gram blood sample was decomposed by a microwave digestion technique followed by dilution to 100.0 mL in a volumetric flask. Aliquots of the sample solution were treated with a lead complexing reagent and water as follows: Solution 1: 10.0 ml blood sample + 20.0 mL complexing agent + 30.0 mL H20. Solution 2: 10.0 ml blood sample + 20.0 mL complexing agent + 26.0 mL H20 + 4.00 mL of 78 ppb Pb2+ standard. The resulting solutions were analyzed by UV/Vis at 375 nm. Absorbance for solution 1 = 0.155 and for solution 2 = 0.216. Calculate the concentration of lead (ppb) in the original sample.
A sample of pure CaCO3 (FW= 100.1 g/mol) weighing 0.350g was dissolved in concentrated HCI (MW= 36.45 g/mol) and diluted to 250mL in a volumetric flask. A 50.0mL aliquot required 35.00mL of an EDTA solution for titration. A 5.0-mL water sample to be analysed for its hardness was diluted to 250mL. A 10.00mL aliquot required 24.50mL of the EDTA solution to reach the EBT endpoint. 1. Calculate the molarity of the EDTA solution. 2. Calculate the water hardness in pm CaCO3.